Oil cracking apparatus



June 20, 1933. v w. v. ISCHIE 1,914,373

OIL CRACKING APPARATUS Filed Aug. 15, 1931 2 Sheets-Sheet 1 INVENTOR VV/W/Qm V. [Sch/22 ATTORNEYS June 2% 1933.

W. v. LSCHIE 1,914,373 OIL CRF CKING APPARATUS Filed Aug. 15, 1931 2 Sheets-Sheet 2 IXI avens/7 919 0/ fl/czp on? for fer/dud 27/7 INVENTOR Z V/Y/I'Qm 4 [SC lie ATTORN EYS Patented June 29, 1933 UNITED stares PATENT GFFHCE WILLIAM V. ISCI-IIE, OF CHICAGO, ILLINOIS, ASSIGNOR TO SINCLAIR REFINING COM- PANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE OIL CRACKING APPARATUS Application filed August 15, 1931.

This invention relates to improvements in apparatus for cracking higher boiling oils such as gas oil and topped crude oil to produce lower boiling oils such as gasoline. The invention relates particularly to improvements in oil cracking apparatus comprising a heater in which oil is heated to a cracking temperature under superatinospheric pressure and an evaporator in which the hot oil productsdischarged from the heater are separated into a vaporized fraction and a residual fraction under a lower pressure.

The reduction of the pressure on the hot oil products discharged from the heater into the evaporator involves a number of difficulties peculiar to cracking operations carried out in this type of apparatus, particularly where the oil is heated to a high cracking temperature, upwards of 900 F, for example, in the heater. The expansion of the hot oil products, upon pressure reduction, involves a tendency toward the for-- mation of solid or semi-solid carbonaceous aggregates immediately in the region of ex pansion. The tendency is accentuated, particularly if the oil is heated to a high cracking temperature in the heater, by any abrupt changes in direct-ion or velocity of flow of the stream or of parts of the stream of hot oil products discharged from the heater into the evaporator. These aggregates deposit and accumulate on the low pressure side of conventional reducing valves, or in the connections between conventional reducing valves and the evaporator, with a consequent tendency to choke the apparatus at this point rendering the operation irregular and uncertain and frequently compelling termination of the operation. These and related difiiculties are largely eliminated in the improved apparatus of the present in vention.

In the oil cracking apparatus of this in vention difficulties due to deposition of solid or semi-solid carbonaceous aggregates adjacent the low pressure side of the pressure reducing valve are substantially eliminated. The apparatus provides for continuously smooth and undisturbed flow of the hot oil Serial No. 557,249.

products constituting the heater discharge from the heater into the evaporator. Operation of the apparatus is regular and certain. The apparatus further embodies peculiar advantages of accessibility.

The improved apparatus of the present invention comprises, in combination with such oil cracking apparatus, a tubular member opening into the evaporator through an aperture in the wall of the evaporator the inner end of which tubular member forms a valve seat, a valve plug positioned with respect to this valve seat by an operating extension extending across the evaporator and through the wall oi the evaporator opposite this aperture, and means for conducting the heater discharge into the evaporator through this tubular member. .This tubular member is advantageously secured in position by means arranged outside of the evaporator to be removable from the out side of the evaporator. That part of the operating extension positioning the valve plug which is within the evaporator is advantageously stiffened and supported by a frame arranged within the evaporator carrying a plurality of supports for this operating extension. The operating parts of the pressure reducing valve within the system, including the means employed to prevent escape of hot oil products along the operating extension, are thus arranged entirely within the region of lower pressure. Easy access to the co operating parts of the pressure reducing valve is provided. Continuously smooth and undisturbed flow of the heater discharge up to the point of expansion is afforded. The deposition of solid or semi-solid carbonaceous aggregates adjacent the pressure reducing valve is prevented. Within the evaporator itsel'l suiiicient volume to accommodate any solid or semi-solid carbonaceous aggregates formed in any reasonable period of operation is easily provided.

The apparatus of the invention is of special value and application in conjunction with operations in which continued cracking in the evaporator of the hot oil products discharged from the heater is limited by appropriate introduction into the system of relatively cool oil. This limitation of further cracking of the hot oil products discharged from the heater is sometimes designated quenching. This operation may or may not involve cracking, in the evaporator, of the oil introduced for this purpose, depending upon the character of this oil and the conditions prevailing in the evaporator.

The apparatus of the invention will be further described in connection with the accompanying drawings which illustrate, diagrammatically and conventionally, an embodiment of the invention. In the accompanying drawings, Fig. 1 is a section of an evaporator in apparatus embodying the in vention, Fig. 2 is a fragmentary section on line 22 of Fig. 1, and Fig. 3 is an elevation, partly in section and with parts broken away, of an apparatus embodying the invention.

In the apparatus illustrated in Fig. 3, charging oil is forced, by means of pump 6, through the heater 7, in the heater 7 this oil is heated to a cracking temperature, 850- 950 F. for example, and the hot oil products are discharged through connection 8 under a superatmospheric pressure, 400-800 pounds per square inch for example, into the evaporator 9 in which a lower pressure is maintained, 1050 pounds per square inch for example, the vaporized fraction separated in the evaporator 9 is discharged through connection 10, to a fractionating system for example, and residual oil is discharged through connection 11. The charging oil may comprise raw oil or one or more higher boiling fractions separated in such fractionating system or a mixture of raw oil and one or more such higher boiling fractions. The reduction in the pressure on the oil between the heater 7 and the evaporator 9 in this system illustrates the reduction of pressure involving the difiiculties to which reference has been made. In the apparatus of this invention the connections between the heater and the evaporator provide for continuously smooth and undisturbed flow of the heater discharge up to the point of pressure reduction or expansion which point is located within the evaporator.

The heater discharge is conducted into the evaporator, in the apparatus illustrated, through the tubular member 12. The inner end of this tubular member forms a valve seat 13.- A valve plug 14 is positioned with respect to this valve seat by an operating extension 15 extending across the evaporator 9 and through the wall of the evaporator opposite the aperture 16 through which the tubular member 12 extends. The valve plug 14 itself is the first and only obstruction the heater discharge meets until expansion to the pressure prevailing in the evaporator has been completed.

are integral. The tubular member 12 slides through a corresponding bore in the flange fitting 18. The tubular member 12 comprising the valve seat 13 is secured in position by means of the flange 17 (see Fig. 1). Thus by unbolting this flange the tubular member 12 can be removed from the outside of the evaporator.

The operating extension 15 carrying the valve plug 14 slides through a plurality of supporting blocks 19, 20 and 21 carried by a frame 22 (see Figs. 1 and 2) arranged within the evaporator 9. Rotation of the operating extension 15 may be prevented by a key 23 as illustrated.

The operating extension 15 extends through the aperture 24, opposite the aperture 16, and through a stufiing box 25 to an appropriate mechanism, corresponding for example to the mechanism for operating a geared gate valve, operated by the hand wheel 26 for accurately positioning and fixing the position of the valve plug 14 with respect to the valve seat 13.

Relatively cool oil may be introduced into the evaporator, for example, through the connection 34 as illustrated in Fig. 3. 'It will be understood that although such quenching oil is relatively cool with re spect to the hot oil products discharged from the heater, it may nevertheless be at elevated temperature, as high as 600650 F., or even higher for example, where the temperature of the hot oil products discharged from the heater approximates 900- 950 F.

It will be apparent that, in the apparatus of this invention, any solid or semi-solid carbonaceous aggregates formed or separated as a result of the expansion of the hot oil products discharged from the heater as they pass between the valve seat and the valve plug are afi'orded no opportunity to deposit in the region adjacent cooperating parts of the valve and, of course, since the valve seat is in effect Within the evaporator there is no opportunity for such aggregates to deposit in any connection between the valve and the evaporator. Any aggregate so formed may deposit in the lower end of the evaporator, but since adequate volume is easily provided at this point to accommodate such material this is at most of but minor consequence. The tubular member of which the valve seat is part is easily removed for inspection, repair or replacement. Such removal involves but a minimum disturbance of the apparatus and does not involve entrance into the evaporator. The several features of the apparatus cooperate to make possible uniform operation over long periods of time.

I claim:

1. In combination in oil cracking appara- The tubular member 12 and th fl ng 17 tus comprising a heater in which oil is heated to a cracking temperature under superatmospheric pressure, an evaporator in which the hot oil products discharged from the heater are separated into a vaporized fraction and a residual fraction under a lower pressure and means for maintaining a higher pressure on said heater, a tubular member opening into the evaporator through an aperture in the wall of the evaporator the inner end of which forms a valve seat, said tubular member being removable from the outside of said evaporator and being secured in position by means arranged outside of said evaporator, a valve plug positioned with respect to said valve seat by an operating extension extending across the evaporator and through the wall of the evaporator opposite said aperture, and means for conducting the heater discharge into the evaporator through said tubular member.

2. In combination in oil cracking apparatus comprising a heater in which oil is heated to a cracking temperature under superatmospheric pressure and an evaporator in which the hot oil products discharged from the heater are separated into a vaporized fraction and a residual fraction under a lower pressure, a tubular member opening into the evaporator through an aperture in the wall of the evaporator the inner end of which forms a valve seat, a valve plug positioned with respect to said Valve seat by an operating extension extending across the evaporator and through the wall of the evaporator opposite said aperture, a frame within the evaporator carrying a plurality of supports for that part of said extension within the evaporator, and means for conducting the heater discharge into the evaporator through said tubular member.

3. In combination in oil cracking apparatus comprising a heater in which oil is heated to a cracking temperature under superatmospheric pressure, an evaporator in which the hot oil products discharged from the heater are separated into a vaporized fraction and a residual fraction under a lower pressure and means for maintaining a higher pressure on said heater, a tubular member opening into the evaporator through an aperture in the wall of the evaporator the inner end of which forms a valve seat, said tubular member being secured in posi tion by means arranged outside of said evaporator, a valve plug positioned with respect to said valve seat by an operating extension extending across the evaporator and through the wall of the evaporator opposite said aperture, means for introducing relatively cool oil into the evaporator, and means for conducting the heater discharge into the evaporator through said tubular member.

' In testimony whereof I afiix my signature.

' WILLIAM V. ISCHIE. 

